Write a Extension Method to give first four character as Capital letter in C#

 --Below is the input

--Below is the output

--Below is the code snippet

class Program

{

    static void Main(string[] args)

    {

        Console.WriteLine("Enter a String");

        string inputStr = Console.ReadLine();

        string strResult = ExtensionMethod.GetString(inputStr);

        Console.WriteLine(strResult);

        Console.ReadLine();

    }

}

public static class ExtensionMethod

{

    public static string GetString(this string str)

    {

        char[] chars = str.ToCharArray();

        string outputStr = string.Empty;

        for (int i = 0; i <= chars.Length - 1; i++)

        {

            if (i < 4)

            {

                outputStr += chars[i].ToString().ToUpper();

            }

            else

            {

                outputStr += chars[i];

            }

        }

        return outputStr;

    }

}